I updated - really haven't noticed much of a difference yet on my First-Gen iPhone (picking up my white 16g tomorrow!).
Of course, I did a full restore a couple of weeks ago which cured 95% of the 2.0-issues that I was having.

I updated my 3g iphone just now, and I tried out the GPS in the parking lot at work...it seems like they fixed the GPS. I zoomed in and could see my little blue dot moving around the map very accurately. I'll try it in the car on the way home. Hopefully, we'll all have turn-by-turn soon!
Otherwise, I can't really tell the difference...oh! Email doesn't seem to lag so much anymore...I used to get weird delays while checking email or opening messages.

Download seemed to go smoothly, and relatively quickly considering the file size. iTunes is now backing up my iPhone, and the blue progress bar seems to have stalled out or is moving at an imperceptible speak. I'm trying to stay awake until it's done, since this phone is my alarm clock.

I just updated with no problems. The first thing I tried is the contacts, as it has always been sluggish when opening and trying to jump to a letter. After the update there was no delay at all, and was amazingly fast. Rock on Apple!

Downloaded. Installed. Nothing out of the ordinary, cept that we're gonna be hit with a massive lightening and thunder storm in five minutes. Things feel better, but that's a judgment call, will know more in the next day or so as I use it.

i have the 2g model.. downloaded and ran the update all went well then BANG "itunes could not connect to iphone; passcode locked" or something of that sort and my iphone just glowed the APPLE symbol and nothing. for 30 minutes i waited .. then i did the softrestart and tried again. this time disableing my lock. it works fine. SO DISABLE LOCK FEATURE BEFORE RESTORING. and good luck

I advise all to download the latest version of iTunes beforehand. The keyboard is still slow, bit the contacts problem is pretty well fixed. Safari doesn't seem snappier. I just did a full restore yesterday. That didn't fix anything. 8 gig 3G.
I've had great sucess with the gps. Always have. Very accurate. Some apps crash. When safari crashed the phone I decided to do a full restore, and it took forever. I just wish I had the option to back up the phone for snappier music swapping.

Just downloaded the update and I still have bugs! The keyboard isn't snappier it lags just as
much as it used too. Some of my downloaded apps STILL don't work!! I'll post up any other bugs I encounter.

-Download and install was about 12 minutes.
-Keyboard is snappier.
-GPS was working fine before, and seems a little more sensitive now.
-Contacts List lagging looks fixed.
-My transition to the iPod also seems quicker.
-Safari is still crashing on occasion, usually when there is more than one page open.

@ jones boy.... I feel your pain. Want a white one too, but was told in my O2 store yesterday that they're not sure they're ever going to get them in. Maybe Apple are holding them for themselves, as Carphone W/house only seem to be selling black 16gb's too?! For me this just means waiting 'til end of 12 month contract and buying direct from Apple rather than upgrading now at 11 months from my Nokia with O2, which does suck but after choosing not to opt for 1st gen. I figure I've waited long enough....so what's another four (SODDING) weeks?! (Cries inconsolably into coffee)

I downloaded it today. Installation was smooth and effortless and WOW. I noticed a significant snappiness and smoother transition between apps and functions. My Safari performance was faster too. I've had the 3G for 3 weeks (since launch date) and after being a Blackberry user for many years in the business world - I am just amazed at what an incredible device and user experience Apple has generated. It's also the best darn quality audio phone I've had.

Jones Boy - I live in the US - bought my first-gen iPhone in October of last year so I'm eligible to upgrade mine.
I ordered it through direct fulfillment last Wednesday and it's enroute to the AT&T store as we speak. When I placed the order, there was a 3-day wait for the white and a 23-day wait on the black - I was on the fence for a bit and still haven't actually seen a white 3G in person - but I'm glad I'm getting the rarer of the two.
RE: 2.0.1 - I've been using my phone a bit more this morning, and also sync'd some more music to the phone. After the sync, it feels much quicker than it did before.

After the update on my iPhone 3G (which I got yesterday) the GPS is much more accurate. I typed in the address bar where I was and every time I zoomed in that pin was smack dab in the middle of the dot. and there wasn't a blue semi-transparent ring around it like before.

I'm getting maybe on average one more bar on Edge and getting 1-2 bars in areas of my house where I used to not have any service.
Contacts has like maybe a second lag when it first opens up, but is substantially improved over what it used to be.
Cell tower triangulation is slightly more accurate than it was.
Haven't had a crash or reset yet, but I didn't have those all that often anyway.
typing lag seems to be better
safari and other web-based apps seem to be slightly snappier.
I think of this update as a really good tune-up.

I'm not sure if this happened before or after the update but my maps is refusing to locate me! Is skyhook down? Used to find me within 2 seconds when on a known wifi router.
I'm on a first generation model in the uk (London)

I upgrade it since last night, and as all of above say, keyboard much faster as well as contact list. But 3g network is switch to Edge very often last night and entire today I don't see any signal of 3g at all, not sure if where I live AT&T have outages for 3g or not. Does anyone have same issue like me? Thinking about downgrade it back to 2.0 if just my phone have issue with 3g.

I still have the 2.0.0 firmware on Mi 3G iPhone and I have a problem with the wallpaper every time I want to change it, it doesn't it staysthe same? I'm going to download the update tommorow morning to see if it fixes it. Has anyone had this problem before if so what did you do to fix it? And do you think the 2.0.1 firmware update will fix this bug?

I loaded this on my non 3g phone. My bluetooth does not work properly now. I pairs with my bmw but doesnt automatically reconnect anymore. This used to work flawlessly. Damn apple, they fix one thing and break several. Greed.

Well updated the Firmware last night to 2.01 and I now own a famous 'ibrick' - itunes failed to update the software and now will not restore the original settings.
Have a 16GB 3G which doesnt work as a phone or an ipod - so the term Iphone is redundant......

FOUND OUT HOW TO FIX THE 'FIND ME' BUG!!
Since V2.0 my 1st gen iphone stopped finding me on Maps. The reason is because (presumably) Apply linked it with Wi-Fi. To use it post Ver 2.0 you must have Wi-Fi enabled and able to see at least one connection (even if it is locked and you cannot connect to it). Now Find Me works (very acurate and much better than before).
NOTES:
- It will not refresh while you are in the same location.
(I have to move 20-30 feet before it will refresh)
- The icon becomes inactive while the blue circle is on
the screen.

after installing 2.0.1 I didn't notice a difference at all. Until today, I tried to use one of the apps I downloaded from the app store. All three I paid for and now none of them work. They load up to the main screen and crash. The apps are used for work to track mileage and fuel and time. So now I'm back to tracking it by hand and hope I haven't lost the data.

I found out the right way to fix the issue where-in you don't get any signals on t-mobile (or any other GSM carrier) once you upgrade to firmware 2.0 and then downgrade back to 1.1.4...the detailed instructions are at : http://iphone-tmobile-nosignal.blogspot.com/